Fair Value Measurements - Carrying Value and Estimated Fair Value of Financial Instruments (Detail) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Fair Value Of Other Financial Instrument [Line Items]
Derivatives	$ 5,480	$ 7,258
Derivatives	6,691	8,413
Level 1 [Member]
Fair Value Of Other Financial Instrument [Line Items]
Short-term financial assets	1,077	891
Federal funds sold and securities purchased under resale agreements	0	0
Non-derivative trading assets	2,988	2,675
Derivatives	8	10
Securities	19,565	22,048
Commercial loans, net of allowance for credit losses	0	0
Short-term financial liabilities	0	0
Consumer loans, net of allowance for credit losses	0	0
Short-term borrowings designated under fair value option	0
Deposits designated under fair value option	0	0
Non-derivative trading liabilities	500	653
Derivatives	7	8
Long-term debt	0	0
Long-term debt designated under fair value option	0	0
Level 1 [Member] \| Commercial Loans [Member]
Fair Value Of Other Financial Instrument [Line Items]
Commercial loans designated under fair value option and held for sale	0	0
Loans held for sale	0	0
Level 1 [Member] \| Consumer Loans [Member] \| Residential Mortgage [Member]
Fair Value Of Other Financial Instrument [Line Items]
Loans held for sale	0	0
Level 1 [Member] \| Consumer Loans [Member] \| Other consumer [Member]
Fair Value Of Other Financial Instrument [Line Items]
Loans held for sale	0	0
Level 1 [Member] \| Deposits Without Fixed Maturities [Member]
Fair Value Of Other Financial Instrument [Line Items]
Deposits	0	0
Level 1 [Member] \| Deposits With Fixed Maturities [Member]
Fair Value Of Other Financial Instrument [Line Items]
Deposits	0	0
Level 2 [Member]
Fair Value Of Other Financial Instrument [Line Items]
Short-term financial assets	20,059	30,807
Federal funds sold and securities purchased under resale agreements	16,112	1,413
Non-derivative trading assets	7,757	9,722
Derivatives	5,440	7,200
Securities	27,847	21,787
Commercial loans, net of allowance for credit losses	0	0
Short-term financial liabilities	10,672	12,813
Consumer loans, net of allowance for credit losses	0	0
Short-term borrowings designated under fair value option	2,070
Deposits designated under fair value option	4,815	5,378
Non-derivative trading liabilities	169	52
Derivatives	6,661	8,376
Long-term debt	22,250	19,524
Long-term debt designated under fair value option	8,239	8,144
Level 2 [Member] \| Commercial Loans [Member]
Fair Value Of Other Financial Instrument [Line Items]
Commercial loans designated under fair value option and held for sale	315	384
Loans held for sale	92	144
Level 2 [Member] \| Consumer Loans [Member] \| Residential Mortgage [Member]
Fair Value Of Other Financial Instrument [Line Items]
Loans held for sale	19	14
Level 2 [Member] \| Consumer Loans [Member] \| Other consumer [Member]
Fair Value Of Other Financial Instrument [Line Items]
Loans held for sale	0	0
Level 2 [Member] \| Deposits Without Fixed Maturities [Member]
Fair Value Of Other Financial Instrument [Line Items]
Deposits	114,005	105,962
Level 2 [Member] \| Deposits With Fixed Maturities [Member]
Fair Value Of Other Financial Instrument [Line Items]
Deposits	1,913	2,813
Level 3 [Member]
Fair Value Of Other Financial Instrument [Line Items]
Short-term financial assets	43	48
Federal funds sold and securities purchased under resale agreements	0	0
Non-derivative trading assets	3,095	3,093
Derivatives	32	48
Securities	0	0
Commercial loans, net of allowance for credit losses	64,490	58,891
Short-term financial liabilities	43	48
Consumer loans, net of allowance for credit losses	18,679	17,896
Short-term borrowings designated under fair value option	0
Deposits designated under fair value option	1,817	1,968
Non-derivative trading liabilities	0	0
Derivatives	23	29
Long-term debt	0	0
Long-term debt designated under fair value option	662	647
Level 3 [Member] \| Commercial Loans [Member]
Fair Value Of Other Financial Instrument [Line Items]
Commercial loans designated under fair value option and held for sale	0	0
Loans held for sale	0	0
Level 3 [Member] \| Consumer Loans [Member] \| Residential Mortgage [Member]
Fair Value Of Other Financial Instrument [Line Items]
Loans held for sale	4	5
Level 3 [Member] \| Consumer Loans [Member] \| Other consumer [Member]
Fair Value Of Other Financial Instrument [Line Items]
Loans held for sale	88	66
Level 3 [Member] \| Deposits Without Fixed Maturities [Member]
Fair Value Of Other Financial Instrument [Line Items]
Deposits	0	0
Level 3 [Member] \| Deposits With Fixed Maturities [Member]
Fair Value Of Other Financial Instrument [Line Items]
Deposits	0	0
Carrying Value [Member]
Fair Value Of Other Financial Instrument [Line Items]
Short-term financial assets	21,179	31,746
Federal funds sold and securities purchased under resale agreements	16,112	1,413
Non-derivative trading assets	13,840	15,490
Derivatives	5,480	7,258
Securities	47,245	43,609
Commercial loans, net of allowance for credit losses	63,099	57,595
Short-term financial liabilities	10,715	12,861
Consumer loans, net of allowance for credit losses	19,870	19,466
Short-term borrowings designated under fair value option	2,070
Deposits designated under fair value option	6,632	7,346
Non-derivative trading liabilities	669	705
Derivatives	6,691	8,413
Long-term debt	21,666	18,733
Long-term debt designated under fair value option	8,901	8,791
Carrying Value [Member] \| Commercial Loans [Member]
Fair Value Of Other Financial Instrument [Line Items]
Commercial loans designated under fair value option and held for sale	315	384
Loans held for sale	92	144
Carrying Value [Member] \| Consumer Loans [Member] \| Residential Mortgage [Member]
Fair Value Of Other Financial Instrument [Line Items]
Loans held for sale	23	18
Carrying Value [Member] \| Consumer Loans [Member] \| Other consumer [Member]
Fair Value Of Other Financial Instrument [Line Items]
Loans held for sale	88	66
Carrying Value [Member] \| Deposits Without Fixed Maturities [Member]
Fair Value Of Other Financial Instrument [Line Items]
Deposits	114,005	105,962
Carrying Value [Member] \| Deposits With Fixed Maturities [Member]
Fair Value Of Other Financial Instrument [Line Items]
Deposits	1,910	2,810
Estimate of fair value [Member]
Fair Value Of Other Financial Instrument [Line Items]
Short-term financial assets	21,179	31,746
Federal funds sold and securities purchased under resale agreements	16,112	1,413
Non-derivative trading assets	13,840	15,490
Derivatives	5,480	7,258
Securities	47,412	43,835
Commercial loans, net of allowance for credit losses	64,490	58,891
Short-term financial liabilities	10,715	12,861
Consumer loans, net of allowance for credit losses	18,679	17,896
Short-term borrowings designated under fair value option	2,070
Deposits designated under fair value option	6,632	7,346
Non-derivative trading liabilities	669	705
Derivatives	6,691	8,413
Long-term debt	22,250	19,524
Long-term debt designated under fair value option	8,901	8,791
Estimate of fair value [Member] \| Commercial Loans [Member]
Fair Value Of Other Financial Instrument [Line Items]
Commercial loans designated under fair value option and held for sale	315	384
Loans held for sale	92	144
Estimate of fair value [Member] \| Consumer Loans [Member] \| Residential Mortgage [Member]
Fair Value Of Other Financial Instrument [Line Items]
Loans held for sale	23	19
Estimate of fair value [Member] \| Consumer Loans [Member] \| Other consumer [Member]
Fair Value Of Other Financial Instrument [Line Items]
Loans held for sale	88	66
Estimate of fair value [Member] \| Deposits Without Fixed Maturities [Member]
Fair Value Of Other Financial Instrument [Line Items]
Deposits	114,005	105,962
Estimate of fair value [Member] \| Deposits With Fixed Maturities [Member]
Fair Value Of Other Financial Instrument [Line Items]
Deposits	$ 1,913	$ 2,813

Fair Value of Commercial Syndicated Loans Held For Sale

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Interest bearing deposits domestic fair value option disclosure.

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This element represents the portion of long term debt that the entity has elected to value at fair value under the fair value option.

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Non-derivative trading assets fair value disclosure.

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Non derivative trading liability.

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Securities, Fair Value Disclosure

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Short-term financial assets fair value disclosure.

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Short-term Financial Liabilities, Fair Value

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Fair value portion of deposit liabilities held by the entity, including, but not limited to, foreign and domestic, interest and noninterest bearing, demand deposits, saving deposits, negotiable orders of withdrawal (NOW) and time deposits.

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No definition available.

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Fair value portion of federal funds sold and securities borrowed or purchased under agreements to resell.

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Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of commercial loans and leases receivable including, but not limited to, commercial and industrial loans, agricultural loans, mortgage loans, promissory notes, interbank and other loans to financial institutions, draws against credit facilities, trade financing, lease financings. Excludes loans and leases covered under loss sharing agreements.

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Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of consumer loans, including, but not limited to, mortgage, home equity, vehicles, credit card, installment, and lease financing. Excludes loans and leases covered under loss sharing agreements.

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- Definition

Fair value portion of loans held-for-sale including, but not limited to, mortgage loans and finance receivables.

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The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

No definition available.

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This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents the amount of short-term debt existing as of the balance sheet date.

+ References

No definition available.

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